HYDRO28488

• Permit No: C1981041
• IBM Index Class Name: Hydrology
• Doc Date: 9/15/2004
• Doc Name: Amendment No. 1 to CDPS Permit No. CO-0027146
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

Snowcap Coal Co. Inc WWTF Water Quality Assessment CO-0027146

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Tem °C Table A-4
Ambient Water Quali for the Colorado River ~ni
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e ~ a ~ r~"°a''k
': t S'4 ' C f~ - YS
t ~ t ~ E!~.~'~`f'a Vi ~
~'limp~le~ seer. P~ Vie„ ; .ereent{ a =Percent~rl,, iit~ean'',, tmr ~ aNot s~'
249 3.7 12 17 11 30
DO 148 8.4 9.5 I1 9.6 5
H su 158 8.2 8.4 8.7 8.4 6.5-9
Fecal Coliform (#/ 100
ml)
2
115
Ill
119
117
200
1
As, Tot u 13 0 0 0 0 NA 2
Cd, Tot u 1 48 0 0 0.39 0.17 NA 2
Cu, Tot u 47 2.2 3.3 9.1 6.0 NA 2
Fe, Tot u 1 48 248 695 2512 2269 NA
Fe, Dis u 40 0 10 20 14 300 2
Pb, Tot u 1 48 0 0 4.8 2.4 NA 2
Mn, Dis u 48 3.0 7.3 15 8.0 50
H , Tot u 2 ND ND ND ND 0.010 2,3
Se, Dis u 23 0 0.30 1.0 0.41 4.6 2
A, Dis u 2 0 0 0 0 1.6 2
Z.n, Tot u ) 48 0 27 85 45 NA 2
Nitrite 42 0 0 0.012 0.0044 0.050 2
Nitrate+Nitrite m 1) 42 0 0.13 0.24 0.13 NA 2
NH3. Tot (mg/1) 2 0.053 0.060 0.067 0.060 NA
NHa, Dis (mg/1) 42 0 0.027 0.045 0.026 NA 2
TSS 80 14 73 563 222 NA
Note 1: The calculated mean is the geometric mean. Note that for sununarization purpose, the value of one was used when: there was n
detectable amount because [he geometric mean cannot be calculated using zero.
Note 2: When sample results were below detection levels, the value of zero was used in accordance with [he CO WQCD's standard approach fo
summarvation and avers 'n u es.
Note 3: For the rated parameters, data were found at less than detection levels. The detecton levels, however, were greater than the in-s
standards. In accordance with WQCD's procedures, to detemtination of water quality is nade when the detection levels are greater flan the in
strclm standartls.
III. Water Quantity
The Colorado Regulations specify the use of low flow conditions when establishing water quality
based effluent limitations, specifically the acute and chronic low flows. The acute low flow, referred
to as 1E3, represents the one-day low flow recurring in athree-year interval. The chronic low flow,
30E3, represents the 30-day average low flow recurring in a three-year interval.
Low Flow Analysis
Between the gage on the Colorado River upstream and the discharges, flow from Plateau Creek
enters the river and flow is withdrawn to the Government Highline Canal. To estimate the low flows
\ at the Snowcap WWTF dischazge points, the daily flow at the USGS gage number 09095500,
Appendix A Page 6 of 12 Last Revised 9/15/2003